Telephone amplifier system



Oct. 9, 1923.

M. C. ELLISON TELEPHONE AMPLTFIER SYSTEM Filed 06t- 16 1922 2 Sheets-Sheet 1 A Hna,

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Oct. 9, 1923.

M. C. ELLISON TELEPHONE AMPLIFIER SYSTEM .n lo

llvs/.E/Y'l'lJ MICHAEL C ELL/SON Patented Get. 9, H523.

UHTE STTES MICHAEL CHETWYND EILISON, OF HUTTONS, ENGLAND.

TELEPHONE AMPLIFIER SYSTEM.

Application filed October 16. 1922.

To n?? fief/0m. t may concern.'

Be it known that l, MICHAEL CHETWYND Emisora, a subject ot' the King of Great Britain, residing at Huttons Ambo Hall, in the county of York, llngland, have invented new and useful Improvements in Connection with Telephone Amplifier Systems, of which the following is a specification.

This invention consists principally in a system of telephony without the need of special connecting wires and intended more especially for use in mines, and the like, the said invention providing means by which telephonie communication can be carried on, by means of telephonie or like, apparatus, without the' necessity for connecting wires between such apparat-us. I employ two carths. or two carthed metallic conductors, oran earth and an earthed metallic conductor, (which. for brevity, I will refer to as the earths) as the means for obtaining the required communication so that conversation can be carried on between places at a distance apart in a mine, or the like, or between the mine and the surface above, or the entrance to, the mine, or the like.

The transmitting apparatus employed in accordance with this invention may comprise a direct current circuit with a microphone therein to cause fluctuations in the current and flowing between the two earths, or a circuit with a current (having fluctuations caused therein by a microphone) transformed from the current passing between two earths such, for instance, as carthed meallie conductors constituted by pipes; for example, haulage ropes compressed air pipes. or water-pipes, where such are available, or wire haulage ropes. The receiving apparatus 'may comprise an audio frequency three electrode thermionic valve amplifier, the input terminals of which are connected to two earthed conductors preferably the same as those to which the transmitter is connected although this is not essential.

I may employ any required number of valves. and any type of three electrode receiving valve andaudio frequency intervalve closed iron core transformers arranged in any .suitable manner, or any other amplifying device may be employed.

n the combined transmitting and receiving apparatus the receiving connection can be m'eomplidied by transformers connected in the earth circuit and ringing up can be effected by means of a. relay.

Serial No. 594,850.

The follo\\'ing is an explanation with reference to the accompanying drawings, of how my invention can be performed, but I do not limit myself to the precise details hereinafter described and illustrated.

Figures l and 2 illustrate diagrannnaticallyr how telephonie systems may, in aecor( ance with my invention, be applied t0 a mine from which its analogous applications will also be understood. Figurc illus trates, diagrammatically, a combined transmitting and receiving apparatus suitable for use in accordance with my invention.

The combined transmitting and receiving appa 'atus is mounted, or fixed, in any suitable, or required position in the mine, each apparatus being preferably compaetly arranged within a portable box indicated at A in Figures 1 and 2, to protect the appas ratusl from injury and allow of its being easily moved from placel to place.

In the arrangements illustrated in Figures l and 2 three boxes A, are shown in position, each containing transmittingr and receiving apparatus, but any desired number of such boxes can of course be employed. The electrical circuit from one apparatus to another is, in the arrangement shewn in Figure 1, shewn as being effectedi by connecting one of the two electric mains of the respective appa` ratus to any suitable metallic pipe B, or the like, in the shaft C of the mine and con` necting the other of the two electric mains of the respective apparatus to earth through the earthed plates D, or, if desired, the last mentioned electric mains may be connected to another metallic pipe, or the like in the mine. Instead of connecting either of the mains to a pipe, or the like, the electric mains ot' each apparatus may be connected to earthed plates D and D as shewn in Figure 2, so that both the outgoing and ingoing currents are conducted from one apparatus to another bv earth. l

The combined transmitting and receiving apparatus shewn diagrammatieally in Figure 3 comprises an audio frequency three electrode valve amplifier, having two valves E, and F, connected in cascade by means of iron-cored inter-valve transformers G.

is a step down telephone transformer. The two earthed metallic conductors and (I, are connected to the input terminals b and al of this amplifier, which so ampli ties the faint electrical impulses as to make them clearly audible.

rent mi @animi "in 'istmfmy "whereof have sgne my mun@ im this Spscicnmn m *ne presence of ivm Suwcmbmg wltnesscs.

EHCHAEL CHETWVT'D ELS N.

Q3 'WmiAM CUm'i', DOROT Anmfama HAZELL. 

